Fig. 1.

A: PET-CT scan demonstrating active disease on both sides of the diaphragm and marrow involvement.

i) Single slice coronal low dose CT image.

ii) Single slice coronal attenuation corrected PET image.

iii) Fused CT and PET images (i and ii).

B: Bone marrow trephine biopsy immunostains: i) PAX5 ii) EBER.

C: Pedigree diagram, showing co-segregation of ADA2 variants (N370K and R169Q) and ADA2 activity (measured at Viapath, Purine Research Laboratory, St Thomas' Hospital; in brief sera incubated with adenosine and ADA1 inhibitor for 3 h, products (inosine and hypoxanthine) separated and measured by high performance liquid chromatography; adult normal range in plasma 8.7–30.0 IU/L). Arrow indicates proband.

D: Sanger confirmation in i) Mother ii) Father.

i Mother: Top row shows wild-type sequence. Lower row shows change from G to A at position 506 in the mother changing the codon from CGG (Arginine, R) to CAG (Glutamine, Q): c.506G > A, p.R169Q.

ii Father: Top row shows wild-type sequence. Lower row shows change from C to A at position 1110 in the father changing the codon from AAC (Asparagine, N) to AAA (Lysine, K): c.1110C > A, p.N370K.